1. Field of the Invention
The present invention relates to a method for preparing an oxime. More particularly, it relates to a novel method for producing an oxime whereby an oxime can be produced from a corresponding ketone or aldehyde and a hydroxylamine without producing a by-product of an inorganic salt such as ammonium sulfate.
2. Discussion of Background
For example, cyclohexanone oxime is industrially useful as an intermediate for producing caprolactam as a starting material for nylon. It is usually prepared by reacting cyclohexanone synthesized by various methods, with hydroxylamine.
However, in such a method, it is necessary to use hydroxylamine in the form of an inorganic salt such as a sulfate or hydrochloride for the stability of hydroxylamine, and it is necessary to neutralize such a salt with an alkali such as ammonia in the reaction system. Consequently, a substantial amount of an inorganic salt such as ammonium sulfate is produced inevitably as by-product together with the desired cyclohexanone oxime. Therefore, it has been desired to develop a process for producing a cyclohexanone oxime without producing an inorganic salt such as ammonium sulfate, as by-product. Some proposals have been made, but none of them has been fully satisfactory.